CP2 Regional Sea Boundaries: Atlantic North-West Approaches, Rockall Trough and Faeroe/Shetland Channel, Offshore 1:250k: Anton Dohrn, Hebrides Terrace, Peach, St Kilda, Offshore 1:500k: Central Rockall Basin, SeaVoX Sub-Ocean: NORTHEAST ATLANTIC OCEAN (40W)
This marine geophysical survey took place from 05/07/92 – 06/07/92 in the area of the Barra Fan on board the RV Kommandor Michael. The survey was carried out by the British Geological Survey (BGS), Marine Biological Association and Dunstaffnage Marine Laboratory. The aim of the survey was to investigate the source and fate of methane in marine sediments. Sub bottom seismic profiling data were collected using a Deep Tow Boomer. These data are archived by BGS. Technical details are contained in BGS Report WB/92/27. Report: Dobinson, A. 1992. Barra Fan Project: Geophysical Operations Report - Project 92/02, https://nora.nerc.ac.uk/id/eprint/529922/. GeoIndex Offshore - https://mapapps2.bgs.ac.uk/geoindex_offshore/home.html?cruise=1992/2&.
Deep Tow Boomer: Source: BGS developed deep towed fish based on a Huntec boomer plate. Operating power 0.5kJ to a tow depth of 800m. Motion compensation applied. Hydrophone: Short 1m multi-element array towed behind the fish. Pinger: Edo Western 35/7.0 kHz tranducer in towed fish. Tow depth Sm. Power output 10kW using SlSA-248 transceiver. Transducer operated in 7.0 kHz mode. Bathymetry: Atlas Deso 20 with narrow beam deep water 33 kHz transducer rated to 2200m. Data also output digitally to Qubit Trac IV logging system. Positioning System: VERIPOS differential GPS system based on Sercel NR 103 DGPS receiver. This fully integrated unit received both GPS data and differential correction data, carried out the corrections processing and output a differentially corrected position to the Qubit Trac IV logging system. Correction data were received from shore stations at Wick, Brest and Barra. Two completely independent VERIPOS receivers were operated simultaneously giving 100% back up. Data Logging: Qubit Trac IV navigation processor/logger. Using position information input from the VERIPOS system the logger produced navigation information, helmsman display, track plotting to AO drum plotter and fix outputs at 5 minute intervals to all survey recorders, whilst logging navigation and bathymetry survey data at half minute intervals to magnetic tape. Seismic Firing Control: BGS seismic control unit to synchronise firing of pinger and deep tow boomer to allow concurrent operation. Firing interval of boomer was 2~ seconds with interleaved firing of pinger to allow 1 second shot interval. An inhibit pulse was provided to the echo sounder at pinger shot instant. For more information see the report, https://nora.nerc.ac.uk/id/eprint/529922/.
unrestricted use, copyright acknowledgement
Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced British Geological Survey materials "Contains British Geological Survey materials ©UKRI [year]"